"Kubuntu has been my favorite Linux distribution since the very first release. It was made specifically for us KDE fans, branded with beautiful Kubuntu-specific artwork and themes, contained the best Qt-based software, and dared to be different. In a world ruled by Ubuntu, it's given us KDE fans something to root for. Unfortunately, Kubuntu later became known as Canonical's third wheel, and each release seems to steadily diminish in quality. What's responsible for its current status, and what should be done to improve it?"

I agree, I am using it since 6.06.
Now I am still using 9.04 and waiting for RC to install 9.10. I must say that 9.04 is perfect, I didn't have any problems with it and I have upgraded to KDE 4.3 since KDE 4.3 was still in beta.
Kubuntu was only in problem during the transition from KDE 3.5 to KDE 4. Now it's only getting better so it's in upward spiral if you ask me.